1. Technical Field
The present invention relates to a data storage apparatus provided with a plurality of hard disk drives, particularly relates to a data storage apparatus, which performs a complete deletion process of a storage area.
2. Description of the Related Arts
In order to prevent that confidential information is revealed from the data remaining in the hard disk drive, various data deleting methods are proposed. For example, there is an image processing apparatus aiming at the increase in efficiency of processing by performing deletion processing only for the field where still new data has not been overwritten among the fields into which data has been written (for example, refer to Unexamined Japanese Patent Application Publication No. 2005-159550). Further, there is a technology of altering a deleting method according to the type and importance of data, which has been written onto the medium (for example, refer to Unexamined Japanese Patent Application Publication No. 2004-363834). Further more, when discarding an image processing apparatus, such as a copying machine, due to purchasing a new one, there is an apparatus provided with the function which destroys data in the hard disk drive mounted in this apparatus based on the instruction from a user (for example, refer to Unexamined Japanese Patent Application Publication No. 2004-48452).
In the case of a hard disk drive, there is a possibility that former data which has been deleted once by fixed data is restored from the magnetic characteristic. Then, various safer deleting methods which are listed below have been proposed and have been standardized.
[Mode 1]
Standard: Russian standard method (GOST P50739-95), JEITA (Japan Electronics and Information Technology Industries Association) recommendation.
Contents: overwrite of 0x00, a number of STEPS: 1 time
[Mode 2]
Standard: U.S. National Security Agency method (NSA standard)
Contents: random number overwrite->random number overwrite->overwrite of 0x00, a number of STEPS: 3 times
[Mode 3]
Standard: U.S. computer security center method (NCSC-TG-025): U.S. Navy method (NAVSO P-5239-26): U.S. Department of Defense method (DoD 5220.22-M)
Contents: overwrite of 0x00->overwrite of 0xFF->random number overwrite->verification, a number of STEPS: 4 times
[Mode 4]
Standard: U.S. Army method (AR380-19)
Contents: random number overwrite->overwrite of 0x00->overwrite of 0xFF, a number of STEPS: 3 times
[Mode 5]
Standard: Old U.S. National Security Agency (NSA standard)
Contents: overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite of 0xFF, a number of STEPS: 4 times
[Mode 6]
Standard: North Atlantic Treaty Organization standard method (NATO method)
Contents: overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite of 0xFF->random number overwrite, a number of STEPS: 7 times
[Mode 7]
Standard: German standard method (VSITR)
Contents: overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite of 0xFF->overwrite of 0xAA, a number of STEPS: 7 times
[Mode 8]
Standard: U.S. Air Force method
Contents: overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite of 0xFF->overwrite of 0x00->overwrite Of 0xFF->overwrite of 0xAA->verification, a number of STEPS: 8 times
When exchanging or discarding hard disk drives, it is preferred to delete all the fields of a hard disk drive completely. However, as the capacity of a hard disk drive increases, the processing time for deleting all the fields once becomes long, and the case where it is needed for 1 hour or more is increasing in recent years. In order to improve security degree, when the complete deletion process which deletes the whole storage area in the above-mentioned [mode 8] is performed, for example, the long time of 8 times of a 1 (one)-time deletion will be required.
Further, there is also an apparatus provided with a plurality of hard disk drives. For example, in a color image processing apparatus, the hard disk drives for image data storage may be provided for respective colors. In case where an apparatus equips with a print controller as an option, the hard disk drive for storing font data, which is controlled by a print controller side CPU, may be provided other than the main body side hard disk drive for storing image data and stamp image for overlay, which is controlled by main body side CPU.
Thus, in case where the apparatus has a plurality of hard disk drives, when the apparatus performs one complete deletion process at a time individually, a very long processing time is necessary, which is calculated by multiplying the number of drives to the time which is necessary to carry out the complete delete per a hard drive. When deleting one set at a time individually, there was a problem that it was difficult to grasp managements of a deleted hard drive and an undeleted hard drive, the time required for performing complete deletion of all the hard disk drives and the progress status of work in the whole process.
Therefore, an object of the present invention is to provide a data storage apparatus, which is capable of performing a complete deletion of a plurality of hard drives with an easy and efficient management to solve the above-mentioned problem.